With the Black Box installed, CB’s Pat Downs sets the timing on our engine via laptop.

"Black Box"

Is it possible to combine performance and good mileage? It is with CB Performance's new easy-to-install electronic ignition system.
By Bruce Simurda | April 15, 2014

Photos by Bruce Simurda


The ignition timing on your air-cooled VW is one of those things where more is often better … but then again, more can also be a terrible thing as well! Take for instance a performance-oriented engine — you want enough ignition timing to produce a good all-around powerband, but not so much to create detonation, which can damage the engine. Those seeking the best mileage possible can also benefit quite a bit from increased ignition timing at cruising speed, but that same amount of advance can destroy an engine under hard acceleration. But that’s the nature of the standard mechanical advance distributor — it produces a straight-line timing curve that only takes into account an engine’s speed! But the problem is, most engines respond well to different timing points depending on whether they’re at idle, accelerating, or cruising. And of course, every engine has different requirements, depending on the camshaft specs, compression ratio, valve and port sizes, and carb size. So what the air-cooled VW engine really needs is a distributor that can change ignition timing depending on factors more than just engine speed — like throttle angle/load. A truly efficient distributor is one that can be custom tailored to any engine’s unique needs. And that’s where CB Performance’s new Black Box Programmable Timing Module comes into play.
This chart shows a conventional mechanical advance distributor’s straight advance curve, compared to the computer controlled curve which can be custom tailored to an engine’s needs at different speeds and loads.
The kit comes with the Box, 7-foot Flying Lead harness, connectors, serial cable, and of course the computer program.
This special washer was developed to quickly “lock-out” the advance on a Bosch distributor.
The washer is easily installed in the center of the distributor cam, just below the small screw.
The Black Box can be mounted just about anywhere, such as the fan housing or behind the rear seat.
The Black Box isn’t a distributor, but rather a controller that allows the conversion of an old school mechanical advance distributor to a programmable ignition system. This is accomplished by connecting it between your distributor and coil, which allows the box to then control all timing movement. In order to accomplish this, it is necessary to “lock-out” you distributor’s mechanical advance mechanism so the box controls all timing movement (CB has come up with a simple washer install for Bosch distributors to accomplish this), as well as connect a vacuum line from the manifolds to the box. After these few installation steps, your distributor becomes completely programmable unit. There is an installation CD included with the Black Box with four base timing maps to choose from, two turbo and two naturally aspirated. According to CB, the Black Box has a 21x21 spark table, and is good for up to 10,000 rpm. It incorporates a 5 Bar Map sensor, allowing boosted timing control over 40 psi. It also has an internal low and high end rev limiter (nice feature!), and will connect to ignition points, aftermarket ignition modules (such as Compufire and Pertronix, MSD distributors, and CB’s Magnaspark Ready-to-Run and Magnetic Trigger distributors). Most aftermarket ignition boxes, such as the MSD 6AL, 7AL, Summit and Mallory are also compatible. This unit will work with either 4-, 6- and 8-cylineder engines, and the kit comes complete with a 7-foot Flying Lead harness (allowing a variety of mounting locations, such as behind the rear seat), easy-to use Windows based software (XP, Vista, 7 or 8), and all electrical terminals and serial cables (some computers may require a USB to serial adapter).
Electrically, all you need is wiring to and from the distributor and coil.
You will also need vacuum pickups from all ports.
For dual 2-barrel carbs, CB makes these base plates to eliminate the need to drill and tap the manifolds.
We had the opportunity the drive our ’72 Bug to Farmersville, California where CB’s Pat Downs installed a Black Box on our basically stock 1600cc engine fitted with dual single-barrel Weber carbs, Bosch 009 distributor and 1.25:1 ratio rockers. On the way there we performed a mileage test, which netted a respectable 28.23mpg on Highway 99. After a half-hour installation we spent about an hour testing a variety of different timing scenarios by feel, from 17° at idle to 47° cruising. We eventually found that our engine idled smoothly with 17° initial advance, cruised nicely with 45°, but liked a more common 30° at full throttle. With some 441 different timing settings in the spark table, depending on the engine’s rpm and throttle position (vacuum), you can custom tailor the timing to match your engine. For example, with our settings we cruised along at 3,200 rpm (approx 70mph) with the timing at 45° for maximum mileage, but the moment we stepped on the throttle the vacuum dropped, and timing dropped with it to 30° to prevent detonation — the best of both worlds! And the second mileage test, over the same highway and at the same gas stations, proved that the engine liked it, as it  improved to 31.66mpg, an increase of 3.43mpg, or 12.15%.
The wire from the distributor is now connected to the black box, a new wire from the Black Box is then routed to the coil, and of course, power and ground are connected.
The distributor does need to be advance 60° to align the computer input with the distributor, and then you can set your initial advance. The rest of the timing is computer controlled...
But mileage isn’t the only story behind this interesting device, because with so much control over the timing you can run much more initial advance (as we said, ours was at 17°) for smoother idling and better off the line performance. We ran a few runs with and without the Black Box using our GTech Pro SS Performance Meter and found that with the standard mechanical advance, we averaged 18.95 e.t. in the quartermile at 69.2mph, but with the Black box that time improved to 18.66 at 70.5mph. These are not huge numbers, but for a nearly stock 1600cc engine it’s a nice gain, and proves that you can improve your mileage, and performance too!
Computer management controls incude a setup window that lets you set the proper parameters for your engine (rpm and vacuum range) as well as the rev limiter and two-step limits.
This is the Spark Map where you determine the timing at 441 different points depending upon the engine’s rpm and load (vacuum).
The Dashboard displays current running specs like rpm, timing and vacuum.

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